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stu28

Active Member

• Apr 4, 2015

• #1

HI All

i have tried the search feature but not found answer,

Discovery 1 , 200 tdi ,

i have changed all 4 brake calipers,
Bled the whole system ( several times )
and used new clean fluid on each time.

I have reasonable brakes now and i lock all 4 wheels if i brake hard, but probably a tiny bit more bleeding required.

However the issue i have is the front brakes are binding really bad.
i have greased the back of pads so they cant stick to pistons, and greased under the clip that holds the pads in place. Although the new pads are very tight with the new pins and clips too.

the rear brakes are perfect no binding at all and working as they should.

But fronts even after a 10 min drive get soo hot you can not hold your finger onto the discs?

Any body have the answer i am looking for ?
why lol ?

many thanks in advance

 

Pauldw

Member

• Apr 4, 2015

• #2

you say "the new pads are very tight with the new pins and clips too." - are we talking about tight to push in?

Have you filed off the paint on the pads where they slide top and bottom of the calipers?

Some aftermarket pads can have quite a thickness of paint where the pads physically sit in the calipers...

 

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stu28

Active Member

• Apr 4, 2015

• #3

No the pads slid in easy into place.
only fit tight when i put the 2 clips on top of the pads and push the split pins through that
hold them into place.
that makes the pads tight.

 

Pauldw

Member

• Apr 4, 2015

• #4

Without fitting the anti rattle shim/spring and with the pistons pushed back - can you wiggle the pads freely (the shim is designed to stop this "pad rattle")

If no - again, could be paint on the pads fouling on the pins (you said you've used new pins) or inside the caliers on the pad runs

If yes could be faulty calipers not returning on release, master cylinder holding on slightly. Have you got your old pads to try...?

 

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stu28

Active Member

• Apr 4, 2015

• #5

If i take the spring/shims off the top of the pads,
and calipers are in,

yes they can move freely about 1mm gap each side of the pads.

( it still binds with old pads in too )

The piston was very hard to push back into caliper,

 

jonathanp

Active Member

• Apr 4, 2015

• #6

Hi

Have you used the correct fitting kit ??

Regards

Jonathan

 

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stu28

Active Member

• Apr 4, 2015

• #7

so am i right in thinking,

if i slightly undo side bleed nipples and the pistons return easy then i have a faulty master cylinder ?

 

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stu28

Active Member

• Apr 4, 2015

• #8

HI Jonathon

yes all parts match up new and old,

 

Pauldw

Member

• Apr 4, 2015

• #9

certainly sounding more and more like calipers not returning - if the dust/return seals are too tight, wont retract the pistons fully

 

Pauldw

Member

• Apr 4, 2015

• #10

Sorry - just saw your other comment - if they free off with the nipple open thats showing pressure holding in the system, probably master cylinder

if they dont free off then its the calipers holding the pistons

 

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stu28

Active Member

• Apr 4, 2015

• #11

Sorry Paul i dont follow you.

Dust return seals ?

 

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stu28

Active Member

• Apr 4, 2015

• #12

lol posted at the same time,

got ya !!

so its master cylinder not allowing the fluid to return after the brake pedal is released ?

 

Pauldw

Member

• Apr 4, 2015

• #13

Dust / Return seals

the pistons should have a rubber seal that prevents dust getting at the pison and bore - that exerts a small amount of return, the seals actually inside the caliper are formed in such a way they retun the piston when the hydraulic pressure from the Master cylinder is released

 

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stu28

Active Member

• Apr 4, 2015

• #14

ok

All intact and clean from dirt.

and i have double checked the other points you mentioned.

so i am left with master cylinder issue.

many thanks for your time

 

jonathanp

Active Member

• Apr 5, 2015

• #15

Hi

you said that "Although the new pads are very tight with the new pins and clips too."

This could be what is stopping the pads retraction

They should not be tight. Are you sure you have the correct fitting kit that goes with the new calipers and pads you bought as there are a couple of types. IE there is the large split pin and a leaf spring type clip and there is the rod with a coil spring between the pads with a very small split pin holding it in place at one end.

Regards

Jonathan

 

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stu28

Active Member

• Apr 5, 2015

• #16

Hi

Yes i have the leaf spring held down with the long split pin.

same set up as before ,

1 side of the pads is loose , but on the other it looks like the piston has not retracted enough, as even with the anti rattle clips off the pad is solid tight between piston and disc.

same on the other front too.

if i loosen the same side bleed nipple a touch then the piston goes in a little.